Embodiments of the present invention relates to a wind turbine blade, a method of assembling a wind turbine blade and a spar cap connection piece.
In particular, it relates to a wind turbine blade comprising at least two sections which are joined together and to the manner in which they are connected.
Given the need for ever longer wind turbine blades, it is now well known to produce wind turbine blades in a number of sections which can be transported to a location close to the location of the wind turbine to which they are to be attached. The blades can then be assembled at such a location to avoid the need to transport a full length blade. The use of the smaller sections has further advantage as smaller components can be made in a more controlled process. Further, the ability to join different sections together means that more blade designs can be produced at a lower cost. For example, it becomes easier to extend a blade to improve performance.
There is a significant difference between the facilities available at such as site as compared to those which are available in the factory environment. There is therefore a need to provide joints which are straightforward to assemble in situ.
The applicant has appreciated that there is merit in the idea of using high performance materials and high quality production techniques in order to produce certain parts of the blade. For example, it is beneficial to produce a high quality tip section in order to reduce parasitic mass as any additional mass in the tip section generates significant loads along the remainder of the blade.
However, such materials create a problem with the manner in which these are attached to other components which are made of different materials and using different manufacturing techniques which may not be compatible with the high performance materials.
Further, the applicant is considering the possibility of producing high quality tip sections which can be fitted to blade sections made by third parties. Under the circumstances, any problems of incompatibility between sections are likely to be exacerbated.
These incompatibilities are potentially problematic as the spar caps are primarily responsible for providing the bending stiffness and strength of the blade. These highly loaded components must satisfy the bending strength and stiffness requirements to maintain the structural integrity of the blade even across transitions between potential incompatible segments.